کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10738880 | 1046840 | 2005 | 14 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Structure-activity relationship of the tocopherol-regeneration reaction by catechins
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کلمات کلیدی
Ubiquinol-104-MethylcatecholTOCARO(–)-epicatechinEGCEGCG(+)-catechin - (+) - کاتچینECG - الکتروکاردیوگرام یا نوار قلبepigallocatechin gallate - اپی گالوستاچین گالاتStructure–activity relationship - رابطه ساختار-فعالیتFree radicals - رادیکال آزادAntioxidant activity - فعالیت آنتیاکسیدانیLow-density lipoprotein - لیپوپروتئین کم چگالی یا الدیال LDL - لیپوپروتئین کم چگالی(کلسترول بد)Methyl gallate - متیل گالاتRutin - معمولیReaction rate - نرخ عکس العملunsaturated lipids - چربی های اشباع نشدهTea catechins - کاکتچین چایhigh-performance liquid chromatography - کروماتوگرافی مایعی کاراHPLC - کروماتوگرافی مایعی کاراQuercetin - کوئرستین
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
سالمندی
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
The reaction rates (kr) of 5,7-diisopropyl-tocopheroxyl radical (Toc) with catechins (epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), epigallocatechin gallate (EGCG)) and related compounds (methyl gallate (MG), 4-methylcatechol (MC), and 5-methoxyresorcinol (MR)) have been measured by stopped-flow spectrophotometer. The kr values increased in the order of MR < < MG < EC < MC â¼ ECG < EGC < EGCG in ethanol and 2-propanol/H2O (5/1, v/v) solutions, indicating that the reactivity of the OH groups in catechins increased in the order of resorcinol A-ring < < gallate G-ring < catechol B-ring < pyrogallol B-ring. The catechins which have lower oxidation potentials show higher reactivities. The rate constants for catechins in micellar solution showed notable pH dependence with one or two peaks around pH 9-11, because of the dissociation of various phenolic hydroxyl protons in catechins. The structure-activity relationship in the free-radical-scavenging reaction by catechins has been clarified by the detailed analyses of the pH dependence of kr values. The reaction rates increased remarkably with increasing the anionic character of catechins, that is, the electron-donating capacity of catechins. The mono anion form at catechol B-and resorcinol A-rings and dianion form at pyrogallol B-and gallate G-rings show the highest activity for free-radical-scavenging. It was found that catechins (EC, ECG, EGC, and EGCG) have activity similar to or higher than that of vitamin C in vitamin E regeneration at pH 7-12 in micellar solution.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Free Radical Biology and Medicine - Volume 38, Issue 9, 1 May 2005, Pages 1243-1256
Journal: Free Radical Biology and Medicine - Volume 38, Issue 9, 1 May 2005, Pages 1243-1256
نویسندگان
Kazuo Mukai, Shuji Mitani, Keishi Ohara, Shin-Ichi Nagaoka,